Electrode



W. E. GOOD Nov. 22, 1949 ELECTRODE Filed July 2, 1945 INVENTOR William E. Good.

WITNESSES: W W JWL ATTOR EY Patented Nov. 22, 1949 -William E. .Good, Pittsburgh, .Pa., assignor =to "WestinghouseTElectric "Corporationi. East Pittsburgh,Pa.,' a. corporation" ofPennsylvania .JApplicationiJnlsiZ, 1945, Serial'Noo60 2-,865

Tclaims.

11 .My .invention relates to electrical discharge devices and in .particulartosuch discharge ,deavicesinwhichqelectrons of an electron beam'are velocityemodulated inzpassing-through a, resonat- -ing-. chamber "having. conducting walls-and: after .zexit; fromthe chamber. have their velocities: rewcrsed by arreflector..e1ectrode.so that a' substan- 'tial-portionof. them re;-enter the chamber. Such an arrangement.isrcapable of generating oscilla- :tions of extremely shortwave. length and. maybe ier-media reflex-. type .of ultra-short wave oscillator.

One 1 object r; of ...myv invention is to provide Jan improved .type -of reflector electrode iwhich; shall .ensure. the re-entryi-nto the. chamber-10f a greater --fraction .-of the emerging electrons. than: did: re- ,eflector electrodesxot thcaprior art.

Another .object. of my: invention is to; provide. a reflex roscillatorehaving a= reflector :electrodezof such formas totsubstantiallyxincrease theqwelec- .trical efiiciency of. the oscillation generator.

Stilla another ;object of my inventioneis to :pro-

ride-iandarrangementt-in:which that-configuration hoof-the eelectric fieldtbetween the reflector :electrode and the outlet 0f. the. resonating-chamber amay be: varied in form. at will.

i Still another object, of .my -:invention is to::pro- ,yide-anarrangement .inqwhichi thewconfiguration iof, the electric fieldain the; HQighbOBhOQdC'OflIH-IB refiecton electrode; .may-.-be regulatedrin :iflCCOi'dance with the current or operatingr'yoltage of the reflex oscillation agenerator.

A still further: obj ect of my, invention is taprovide a. reflex-. type of oscillation; generator r-With a .iform OfzIEfiBCtOIY electrode-suitable for experi-,;

mentally varying. the configurationeof the elecl. tric'rfield in the region of the refiectorelectrode to ..determine..the;optimum form suitable fora tube of given-l current and voltage, rating.

illOtherobjectspf.my invention will: become. apparent upon reading the following. description .iitaken' in .connectioniwith the-accompanyingdrawings, .imwhich:

IZFignre... 1 -is 5,3, diagrammatic view, M largely a diametrical section, 1 of .an electrical discharge tube embodying the. principlesofmy invention.

"FigsflZ. and. 3. are; diagrammatic. illustrations of reflector electrode arrangements alternative to the reflectorielectrode (of Fig.1, and

figs. 4, .andfi are diagrams :useful in. explaining =velop which is preferably evacuated, encloses an electron gun. for producing a relatively-concenitratedt-ibeam of electrons. As shown heregthe fgun.includes.-a cathode comprising a heater'5l3 :surrounded by ancemitting memberd i. zElectrons emitted by this cathode are accelerated: to

.. a. desired .velocity shy.- means of anaccelerating :electrode structure it having a smalltopeningylfi- ,inits end through which-ahconcentrated beam-of electrons -.is projected through a grid or other form of. opening ll in the walls of a'conducting resonator or chamheriB. .On the opp-osite'wall .of the chamber l3 inline with the path of the electron -beam passing through the opening I! :is

positioned a second grid or other form of opening 18. throughiwhich the electrons of: the beam may emerge-from the chamber. H3. .A suitable:voltwage source groundedsupplies. heating current tothe heater 2! ,having .-its positive terminal 13. A second: voltage scurce2'2 having itsgnega- -.tive terminal. grounded and connectedto electrode i 5..s1lpl 1ies current to aaypotentiometer a 2 3130i a variable ,tapon "which. is. connected the resonatiing chamber. 18.

{1A5 is-wellsknownpin.the :.art, it. is possible sby adjusting the electricar potential at theopening I! by means-of the associated slider on, potentiometer 29, to give the electrons entering through opening lI-i-ntmchamher |8-,such a'velocitythat ithey. will consume in passing. from. the opening I! to the opening l9 one-half period of thenatural .frequency: of. electrical vibration of the resonant naccelerate. them, will leave the opening l9 one- .halfa cycle later when the electrical field at opening 5 9. tends. likewise: to accelerate them .andawill "accordingly undergo: arnet increase of velocity inrpassingithrough chamber I 8. -Oh the other hand, those electrons-enteringthrough: opening ll1...at"a ,time when the electric field .Withimthe chamber 13 isof such polarity as to retard-them .will.likewiseemerge from the opening l9when the. polarity of the. electric field. there. is sucheas ,toiretardlthem. .The electron :stream israccordingly subdivided into alternatetgroups ofchigher velocity electrons and lower velocity electrons;

-.:and. asthese groups travel forward the electrons will-tend to. become segregated into ibunchesf;

vin other-wordsythe electron'rstream will have is'high-separatedJay-portions in which. the electron .density is'low.

.It is likewise knowni in the art that by po'sibunches or concentrated portions of the electron. stream thus pas-s in the reverse direction through the chamber I8, the electrical vibrations in the latter are reinforced. By suitable arrangements too well known in the art to require description here, electrical energy may be withdrawn for use in external circuits at the frequency of the vibra- I the reflector electrode and the opening is in such a way as to decrease the fraction of the reflected electrons which fail to re-enter chamber i8 through opening I9. I have discovered a number of different forms for the reflector electrode which produce improved results over those of the prior art and thus are shown respectively in Figs. 1, 2, 3 and 4.

Referring in detail to the reflector electrode shown in Fig. 1, it comprises what may be considered to be a spherical surface subdivided by narrow insulating gaps into three sectors or zones 23, 24 and 25, the above mentioned insulating gaps being respectively shown at 25 and 21. Each of the sectors 23, 24 and 25 is connected by a suitable lead-wire to sliders on the potentiometer 20. By adjusting the position of the last mentioned sliders, the form of the electric field inside the reflector electrode and between its adjacent end and the opening I9 can be varied at will to a considerable degree.

In particular it will be noted that if the three sliders connected respectively to the sectors 23, 24 and 25 are positioned at the same point on the potentiometer 23, the electric potential of the zones 23, 24 and 25 are the same and the Zones 23, 24 and 25 thus constitute what is in substantial effect a single spherical surface with an opening aligned with the opening I9 in chamber I8. Preferably the diameter of th spherical surface thus produced is substantially greater than that of the opening I9 so that the spherical surface subtends a solid angle at the center of the sphere which is substantially greater than 21r solid radians. I have found that a reflector electrode of the spherical type thus produced gives very satisfactory results in producing an electric field between its outlet and the grid IQ of such form as to ensure that a large fraction of the reflected electrons re-enter the chamber I8.

However, I have also found that the configuration of the last mentioned electric field which gives optimum re-entry of electrons into chamber Ill depends on the value of the current flowing from cathode I4 through chamber I8 and on other electrical and geometrical parameters of the structure so far described. On that account, it is desirable in the case of some types of reflex oscillator to adjust the sliders on potentiometer 20 so as to set up differences of potential between the sectors 23, 24 and 25. It is possible to determine the positions to be taken by the potentiometer sliders experimentally to give the highest efliciency of the reflex oscillator; and it is also possible by calculation or suitable experiments to determine the configuration of the electric' field between the reflector electrode and the grid I9, and similarly to determine the potentials to be applied to the sectors 23, 24, 25 which will give such optimum configuration by calculation or experiment.

In Fig. 2 I show an alternative form for the reflector electrode which may comprise a cylindrical chamber having a plane end wall 3|, cylindrical side walls 32 and a second end wall 33 having an opening aligned with the grid I9. Suitable lead wires from the wall portions 3|, 32, and 33 lead to sliders on the potentiometer 20 so that the electrical potentials of the wall portions may be adjusted at will. In particular, it will be obvious that when the three sliders connected to the wall portions 3|, 32 and 33 are positioned 'at the same point on the potentiometer 20 the chamber of Fig. 2 will constitute, in effect, a cylinder with equipotential walls having an opening at one end aligned with the grid opening I9.

In Fig. 3 I show still another form of reflector electrode which may be considered to comprise roughly a truncated cone having a base portion 34 with an opening aligned with the opening I9 and having its curved surface divided into two portions 35 and 36 preferably of equal area by a plane passing through the axis of the cones. Each of the zones 34, 35 and 36 is connected by a suitable lead with the potentiometer 20. It will again be obvious that when the potentiometer sliders connected to these leads are placed on the same portions of the potentiometer 20 the reflector electrode will, in effect, comprise a truncated cone having an equipotential surface. It will be noted that if the potentials of the portions 35 and 36 are given different values, the electric field between them and the opening I9 will be dissymmetrical about the axis of the chamber I8.

It will be obvious that both the Fig. 2 and the Fig. 3 reflector electrodes may be considered to comprise surfaces which subtend about a point in their central region a solid angle greater than 27! solid radians.

It is, of course, possible to obtain reflector electrodes which are less flexible electrically to adjustment by omitting either of the gaps 26 or 21 in Fig, 1, or the analogous gaps in Figs. 2 and 3. I have also found that a very useful reflector electrode results if the zone 33 in Fig. 2 is omitted from the reflector electrode surface thereby giving a reflector electrode of the type shown in Figs. 4 and 5. A moments consideration will show that if the electrode 3| is given a less positive potential relative to the electrode 32, the electrical field in the vicinity of the opening I9 will have equipotential lines. in the general form of the dotted lines 31 in Fig. 4. On

the other hand, if the sector 3| is given a more positive potential the equipotential surfaces will have the form shown by the dotted lines 38 in Fig. 5. Figs. 4 and 5 thus illustrate the general character of the alteration of the electric field in the region between the reflector electrode and the opening I9 which results from adjusting the relative potentials of the sectors of the reflector electrode surface.

While I have illustrated the principles of my invention by showing specific embodiments thereof, these principles are of broader application in ways which will be evident to those skilled in the art.

I claim as my invention:

1. Means for producing an electron beam, a cavity resonator mounted along the path of said beam and having conducting walls provided with openings to be traversed by said beam, and a reflector electrode aligned with said openings and comprising a hollow member having walls which subtend, about a point in the central region of the member, a solid angle substantially greater than 271' solid radians, said walls having an opening in the path of said beam.

2. A reflector electrode for an oscillation generator of the reflex type which comprises a hollow sphere having an opening in its surface said surface subtending, about a portion in the central region of said chamber, a solid angle substantially greater than 211' solid radians.

3. A reflector electrode for an oscillation generator of the reflex type comprising a hollow body having a surface of conducting material subdivided into a plurality of zones insulated from each other, and having an opening in the surface of one said zone, the surface of said reflector electrode subtending, about a point in the central region of said reflector electrode, a solid angle substantially greater than 2w solid radians,

4. A reflector electrode for an oscillator of the reflex type comprising a spherical surface having an opening therein and subdivided in a plurality of zones insulated from each other.

5. A reflector electrode for an oscillator of the reflex type comprising a spherical surface having an opening therein and subdivided in a plurality of zones insulated from each other, the surface of said reflector electrode subtending, about a point in the central region of said re- 6 flector electrode, a solid angle substantially greater than 21r solid radians.

6. A reflector electrode for an oscillation generator of the reflex type comprising a hollow cylindrical wall of conducting material, an end wall at one end thereof of conducting material and insulated from said cylindrical wall, and adjustable means connected to said walls for varying the relative electrical potentials of said end wall and said cylindrical wall.

7. An electronic device comprising means for producing an electron beam, a cavity resonator mounted along the path of the beam, said resonator having conducting walls provided with openings to be traversed by the beam, and a reflector electrode aligned with the openings, said reflector electrode comprising a hollow member having a substantial maximum inner cross-sectional area and having an opening in its Wall portion which has an area smaller than the maximum cross-sectional inner area of the hollow member transverse to the path of the beam, the last named opening being adjacent an opening of the resonator.

WILLIAM E. GOOD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Re. 22,506 Hahn June 27, 1944 2,190,511 Cage Feb. 13, 1940 2,259,690 Hansen et a1 Oct. 21, 1941 2,416,714 Pierce Mar. 4, 1947 2,421,273 Lafferty 1 May 27, 1947 FOREIGN PATENTS Number Country Date 665,619 Germany Sept. 29, 1938 

